Stroke Risk in Sleep Apnea Same in Both Sexes

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Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.

Women with obstructive sleep apnea have a risk for stroke which is correlated with severity and similar to that in men.

SAN DIEGO -- A new analysis of a long-term study has found that men and women with sleep apnea are at a similar risk of having a stroke, researchers reported here at the annual meeting of the American Thoracic Society.

The 5-year probability of having a stroke with the least severe obstructive sleep apnea index was 0.4% for women and 0.6% for men, while the probability in the highest quartile of obstructive sleep apnea severity was 1.2% for women and 1.8% for men, reported Suzanne Bertisch, MD, instructor in medicine at Harvard Medical School/Beth Israel Deaconess Medical Center in Brookline, Mass.

At 10 years, the probability of having a stroke if you were in the lowest quartile of the sleep apnea index was 0.9% for women and 1% for men, while the probability of having a stroke in the highest quartile of the apnea index was 2.3% in women and 3.1% in men, she reported.

All results were adjusted for various confounders including age, race, education level, smoking status, diabetes, hypertension, and body mass index, she said.

"Overall, we have found evidence of an increasing likelihood of stroke in women and not just the men," she said. "We are showing that women who reach the threshold for sleep apnea are at risk for cardiovascular disease." She said the study indicated that it just as important in women as in men to attend to cardiovascular risk factors if they are diagnosed with sleep apnea.

Bertisch and colleague re-evaluated the findings of the Sleep Heart Health Study – a study that previously had indicated that sleep apnea was associated with stroke in men but not in women. With more events – 153 strokes reported among women and 113 in men, the researchers found that the significance between men and women has been muted, but the indication that stroke was observed with higher sleep apnea index scores remained.

The researchers followed 5,500 individuals for an average of 11.5 years. "The initial analysis, which was performed after an average follow-up of 8 years, shows an effect of increasing obstructive sleep apnea index severity and a relationship between sleep apnea and stroke in men but not in women," Bertisch said in a press briefing.

The current study report represents outcomes through 2011, Bertisch said. Because 20% of the original cohort had died, the researchers also recalculated the impact of sleep apnea on strokes. "We followed these patients longer, we had more data and we used state-of-the-art analysis," she said.

The new analysis included the 268 strokes that occurred during the study, she said. "When we adjusted for other variables, we found that when compared with the lowest quartiles in both women and men, [there was] evidence of the impact on stroke in people with the highest categories of obstructive sleep apnea index scores," she said.

Press conference moderator David Rapoport, MD, medical director of the sleep disorder unit at NYU Langone Medical Center, commented, "There are lots of studies that have shown that sleep apnea is bad for your risk of stroke. But the majority of strokes happen in men, so it as difficult to show the difference between men and women. One conclusion was that women were protected but what this study adds is that there was no protection, just statistical difficulty proving it until this analysis that they have done.

"What they are showing is that it has similar effects, if not the same magnitude for women as in men. That is an important concept as opposed to women being protected," Rapoport said. "There is good evidence that sleep apnea is slightly less common in women than in men and there is a perception out there that maybe women don't have it: That's wrong. Until recently there was a question in people's minds as to whether sleep apnea mattered less."

He said it is also thought that women are less likely to seek treatment for sleep apnea. "If the consequences were less it would not matter. This adds to the fuel that if it matters, and it matters equally for women as it does for men."

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